"Yeah, because Google never heard of Microsoft and their patents when implementing Android.

But then again, Android was already implemented before Google acquired it. "

Yes, but not fully (Google did modify it a lot I guess) and not that long before Google acquired it and probably after Microsoft did register their patents.

Is your point that Google should be free to use the patented technologies because it was Android (the company) which implemented the OS before the acquisition? In this case, your point is obviously not valid, because when one company acquire another company, they take the full responsibility for everything the acquired company did in the past.